Experimental relations for the hall effect near the metal insulator transition (original) (raw)
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On the nature of the Hall insulator
Solid State Communications, 1997
We have conducted an experimental study of the linear transport properties of the magnetic-field induced insulating phase which terminates the quantum Hall (QH) series in two dimensional electron systems. We found that a direct and simple relation exists between measurements of the longitudinal resistivity, ρxx, in this insulating phase and in the neighboring QH phase. In addition, we find that the Hall resistivity, ρxy, can be quantized in the insulating phase. Our results indicate that a close relation exists between the conduction mechanism in the insulator and in the QH liquid. 73.40.Hm, 72.30.+q, 75.40.Gb
An Experimental Study on the Hall Insulators
We have studied the Hall insulators (HIs) in a gated two-dimensional GaAs electron system containing self-assembled InAs quantum dots. It is shown that the semicircle law can become invalid in the quantum Hall (QH) liquid, so that the quantized Hall plateau is absent at the insulator-quantum Hall (I-QH) transition. The appearance and breakdown of the semicircle law in the insulating phase can both be observed when the QH liquid is destroyed by disorder. From our study, the quantized HI is not necessarily accompanied by the I-QH transition.
Electronic Transport in Expanded Liquid Mercury
We report the results of an experimental study of the electronic transport properties (Hall effect and electrical conductivity) of expanded liquid mercury in the density range 13.6-8.5 g cm+ (temperature region 30-1500'C and pressure region 1-1900 atm). From the correlation of the Hall coefficient and the conductivity, three distinct conduction regimes were identified in this one-component system: (a) the weak-scattering metallic region (13.6-11 g cm), (b) the strong-scattering metallic region (11.0-9.2 g cm+), and (c& the localization regime (&9.2 g cm+). Detailed information has been obtained for the formation of the pseudogap and the metal-nonmetal transition in this disordered system.
Hall-mobility measurements at elevated temperatures and pressures
Journal of Applied Physics, 1973
We describe a system for the measurement of the Hall mobility in expanded liquid metals and in dense metallic vapors at elevated temperatures (30--1600 'C) and pressures (1-2000 atm). Performances of the experimental setup are presented for mercury up to its critical point.
Hall effect in a moving liquid
European Journal of Physics, 2012
A simple experiment, suitable for performing in an undergraduate physics laboratory, illustrates electromagnetic induction through the water entering into a cylindrical rubber tube by detecting the voltage developed across the tube in the direction transverse both to the flow velocity and to the magnetic field. The apparatus is a very simple example of an electromagnetic flowmeter, a device which is commonly used both in industrial and physiological techniques. The phenomenology observed is similar to that of the Hall effect in the absence of an electric current in the direction of motion of the carriers. The experimental results show a dependence on the intensity of the magnetic field and on the carrier velocity, in good agreement with the theory. Discussion of the system, based on classical electromagnetism, indicates that the effect depends only on the flow rate, and is independent both of the velocity profile and of the electrical conductivity of the medium.
Philosophical Magazine B, 1998
The quantized Hall insulator is characterized by vanishing conductivities and a quantized Hall resistance. For low mobility samples, the quantized Hall insulator is obtained when the magnetic field is increased well above the ν=1 quantum Hall state. For higher mobility samples, a similar quantization is observed when the magnetic field is increased above the ν = 1/3 fractional quantum Hall states. This quantization, throughout the quantum Hall liquid-to-insulator transition, leads to a perfect semicircle relation for the diagonal and Hall conductivities. The measurements were performed in Ge/SiGe quantum Wells and in n-type InP/InGaAs and GaAs/AlGaAs heterostuctures.